Kiev, Ukraine (CNN) — As the crisis in Ukraine shows no signs of easing, U.S. Vice President Joe Biden promised support for Ukraine and stressed that the United States won’t recognize Russia’s annexation of Crimea.
“Ukraine is and must remain one country,” he said in Kiev on Tuesday at a press conference with Prime Minister Arseniy Yatsenyuk. Biden also met with acting President Oleksandr Turchynov during his trip to Ukraine.
“No nation has the right to simply grab land from another nation,” Biden said. “We will never recognize Russia’s illegal occupation of Crimea.”
Biden called on Russia to “stop supporting men hiding behind masks and unmarked uniforms sowing unrest in eastern Ukraine.” He warned of additional sanctions if such “provocative behavior” does not end.
Ukrainian and U.S. officials believe Russian special forces are in the region and are behind efforts to seize government buildings and generally promote unrest.
The vice president promised financial support, assistance in reducing Ukraine’s dependence’s on Russian energy sources, and non-lethal aid for security forces
“You will not walk this road alone. We will walk it with you,” Biden told Yatsenyuk.
The backing is likely to sit well with Ukrainian leaders struggling to keep their country afloat amid dire financial problems and a showdown with Russia over its annexation of Crimea and alleged interference in Ukraine’s pro-Russian east.
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An armed pro-Russian man stands on a street in Sloviansk, Ukraine, on Monday, April 21. Ukraine has seen a sharp rise in tensions since a new pro-European government took charge of the country in February. Moscow branded the new government illegitimate and annexed Ukraine’s Crimea region last month, citing threats to Crimea’s Russian-speaking majority. And in eastern Ukraine, pro-Russian separatists have seized government and police buildings in numerous towns and cities.
U.S. Vice President Joe Biden arrives at Boryspil International Airport near Kiev on April 21.
Demonstrators attend a pro-Russian rally outside the secret service building in Lugansk, Ukraine, on April 21.
Cars are burned out after an attack at a roadblock in Slaviansk on Sunday, April 20.
A resident inspects burnt-out cars at the roadblock on April 20.
A pro-Russian militant is seen at the roadblock near Slaviansk on April 20.
Armed pro-Russian militants stand guard at the roadblock near Slaviansk on April 20.
A masked man stands guard outside a regional administration building seized by pro-Russian separatists in Slaviansk, Ukraine, on Friday, April 18.
People walk around barricades April 18 set up at the regional administration building seized earlier in Donetsk, Ukraine.
Russian President Vladimir Putin speaks to the media after a nationally televised question-and-answer session in Moscow on Thursday, April 17. Putin denied that Russian forces are involved in the unrest in eastern Ukraine, though he did admit for the first time that Russians were active in Crimea before the peninsula voted to join the country.
Ukrainian riot police officers stand guard during a pro-Ukrainian demonstration in Donetsk on April 17.
Masked pro-Russian protesters stand guard in front of the city hall in Mariupol, Ukraine, on April 17.
U.S. Secretary of State John Kerry reaches out to shake hands with Russian Foreign Minister Sergey Lavrov at the start of a bilateral meeting to discuss the ongoing situation in Ukraine. The meeting took place April 17 in Geneva, Switzerland.
A masked gunman stands guard near tanks in Slaviansk, Ukraine, on Wednesday, April 16.
A Ukrainian helicopter flies over a column of Ukrainian Army combat vehicles on the way to Kramatorsk, a city in eastern Ukraine, on April 16.
A masked pro-Russian gunman guards combat vehicles parked in downtown Slaviansk on April 16.
A man talks with Ukrainian soldiers as they are blocked by people on their way to Kramatorsk.
Ukrainian soldiers sit atop combat vehicles on their way to Kramatorsk.
Ukrainian Gen. Vasily Krutov is surrounded by protesters after addressing the crowd outside an airfield in Kramatorsk on Tuesday, April 15.
Pro-Russian activists guard a barricade April 15 outside the regional police building that they seized in Slaviansk.
Ukrainian troops receive munitions at a field on the outskirts of Izium, Ukraine, on April 15.
Armed pro-Russian activists stand guard on top of a Ukrainian regional administration building in Slaviansk on Monday, April 14.
A pro-Russian activist carries a shield during the mass storming of a police station in Horlivka, Ukraine, on April 14.
Russian supporters attend a rally in front of the security service building occupied by pro-Russian activists in Luhansk, Ukraine, on April 14.
A man places a Russian flag over a police station after storming the building in Horlivka on April 14.
Men besiege the police station in Horlivka.
The Horlivka police station burns on April 14.
A Ukrainian police officer receives medical care after being attacked at the police station in Horlivka on April 14.
Pro-Russian supporters beat a pro-Ukrainian activist during a rally in Kharkiv, Ukraine, on Sunday, April 13.
Pro-Russian activists escort a man outside the secret service building in Luhansk on April 13.
Pro-Russian protesters guard a barricade in Slaviansk on April 13 outside a regional police building seized by armed separatists the day before.
Armed pro-Russian activists carrying riot shields occupy a police station in Slaviansk on April 12.
A group of pro-Russian activists warm themselves by a fire Friday, April 11, in front of a Ukrainian Security Service office in Luhansk.
Ukrainian Prime Minister Arseniy Yatsenyuk speaks April 11 during his meeting with regional leaders in Donetsk, Ukraine. Yatsenyuk flew into Donetsk, where pro-Russian separatists occupied the regional administration building and called for a referendum.
Pro-Russian young men look over the fence of a military recruitment office in Donetsk on Thursday, April 10.
Armed pro-Russian protesters occupy the Security Service building in Luhansk on April 10.
Members of the self-proclaimed government the “Donetsk Republic” vote April 10 during a meeting at the seized regional administration building in Donetsk.
Ukrainian lawmakers from different parties scuffle during a Parliament session in Kiev, Ukraine, on Tuesday, April 8.
Workers clean up on April 8 after pro-Russian separatists and police clashed overnight in Kharkiv.
Pro-Russian protesters burn tires near a regional administration building in Kharkiv after police cleared the building on Monday, April 7.
A masked man stands on top of a barricade at the regional administration building in Donetsk on April 7.
Protesters wave a Russian flag as they storm the regional administration building in Donetsk on Sunday, April 6. Protesters seized state buildings in several east Ukrainian cities, prompting accusations from Kiev that Moscow is trying to “dismember” the country.
Pro-Russian protesters clash with police as they try to occupy a regional administration building in Donetsk on April 6.
Pro-Russian activists hold a rally in front of a Ukrainian Security Service office in Luhansk on April 6.
A young demonstrator with his mouth covered by a Russian flag attends a pro-Russia rally outside the regional government administration building in Donetsk on Saturday, April 5.
A Ukrainian soldier guards a road not far from Prokhody, a village near the Russian border, on April 5. Ukrainian and Western officials have voiced alarm about Russia’s reported military buildup on Ukraine’s eastern border.
Ukrainian cadets at the Higher Naval School embrace a friend who has decided to stay in the school during a departure ceremony in Sevastopol, Crimea, on Friday, April 4. Some 120 cadets who refused to take Russian citizenship left the school to return to Ukraine.
Soviet military veterans take part in a flower-laying ceremony at the Soviet-era World War II memorial in Sevastopol on Thursday, April 3.
Ukrainian soldiers conduct a training session on the Desna military shooting range northeast of Kiev on Wednesday, April 2.
Russian soldiers prepare for diving training in front of a Tarantul-III class missile boat Tuesday, April 1, in Sevastopol.
People pass by barricades near the Dnipro Hotel in Kiev on April 1.
People walk past a train loaded with Russian tanks Monday, March 31, in the Gvardeyskoe railway station near Simferopol, Crimea.
A Russian solder sits in a tank at the Ostryakovo railway station, not far from Simferopol on March 31.
Russian Prime Minister Dmitry Medvedev speaks about the economic development of Crimea during a meeting March 31 in Simferopol.
Members of the Ukrainian National Guard take part in military exercises on a shooting range near Kiev on March 31.
A woman cries Sunday, March 30, during a gathering to honor those who were killed during protests in Kiev’s Independence Square.
A woman and child walk past a line of police officers during a rally in Kharkiv on March 30.
Ukrainian soldiers take part in a training exercise at a military base in Donetsk on Saturday, March 29.
Demonstrators protest Friday, March 28, in Kiev, displaying police vehicles they seized during earlier clashes with authorities.
Members of the Right Sector group block the Ukrainian parliament building in Kiev on Thursday, March 27. Activists called for Interior Minister Arsen Avakov to step down after the recent killing of radical nationalist leader Oleksandr Muzychko, who died during a police operation to detain him. Muzychko and the Right Sector are credited with playing a lead role in the protests that toppled Ukrainian President Victor Yanukovych.
Ukrainian tanks are transported from their base in Perevalne, Crimea, on Wednesday, March 26. After Russian troops seized most of Ukraine’s bases in Crimea, interim Ukrainian President Oleksandr Turchynov ordered the withdrawal of armed forces from the Black Sea peninsula, citing Russian threats to the lives of military staff and their families.
Ukrainian marines wave as they leave a base in Feodosia, Crimea, on Tuesday, March 25.
Russian sailors stand on the deck of the corvette ship Suzdalets in the bay of Sevastopol on March 25.
Pro-Russian militia members remove a resident as Russian troops assault the Belbek air base, outside Sevastopol, on Saturday, March 22. After its annexation of Crimea, Russian forces have consolidated their control of the region.
Soldiers in unmarked uniforms sit atop an armored personnel carrier at the gate of the Belbek air base on March 22.
A Russian sailor holds the Russian Navy’s St. Andrew’s flag while standing on the bow of the surrendered Ukrainian submarine Zaporozhye on March 22 in Sevastopol.
Russian President Vladimir Putin signs the final decree completing the annexation of Crimea on Friday, March 21, as Upper House Speaker Valentina Matviyenko, left, and State Duma Speaker Sergei Naryshkin watch.
A Ukrainian serviceman leaves a Ukrainian military unit that Russian soldiers took control of in Perevalne on March 21.
Ukrainian border guards run during training at a military camp in Alekseyevka, Ukraine, on March 21.
Russian soldiers patrol the area surrounding a Ukrainian military unit in Perevalne on Thursday, March 20.
Pro-Russian protesters remove the gate to the Ukrainian navy headquarters as Russian troops stand guard in Sevastopol on Wednesday, March 19.
Pro-Russian forces walk inside the Ukrainian navy headquarters in Sevastopol on March 19.
A member of pro-Russian forces takes down a Ukrainian flag at the Ukrainian navy headquarters in Sevastopol on March 19.
Alexander Vitko, chief of the Russian Black Sea Fleet, leaves the Ukrainian navy headquarters in Sevastopol after pro-Russian forces took it over on March 19.
A Russian flag waves as workers install a new sign on a parliament building in Simferopol, Crimea’s capital, on March 19.
Russian military personnel surround a Ukrainian military base in Perevalne on March 19.
Nameplates on the front of the Crimean parliament building get removed Tuesday, March 18, in Simferopol.
From left, Crimean Prime Minister Sergey Aksyonov; Vladimir Konstantinov, speaker of the Crimean parliament; Russian President Vladimir Putin; and Alexei Chaly, the new de facto mayor of Sevastopol, join hands in Moscow on March 18 after signing a treaty to make Crimea part of Russia.
Demonstrators hold a Crimean flag at Lenin Square in Simferopol on March 18.
Ukrainian soldiers stand guard at a checkpoint near Strilkove, Ukraine, close to Crimea on Monday, March 17.
Former boxer and Ukrainian politician Vitali Klitschko addresses reporters in Kiev on March 17.
Ukrainian troops stand guard in front of the Ukrainian Parliament building in Kiev on March 17.
A Ukrainian man applies for the National Guard at a mobile recruitment center in Kiev on March 17.
Civilians walk past riot police in Simferopol on March 17.
A Ukrainian soldier stands on top of an armored vehicle at a military camp near the village of Michurino, Ukraine, on March 17.
Policemen stand guard outside the regional state administration building in Donetsk during a rally by pro-Russia activists March 17.
Armed soldiers stand guard outside a Ukrainian military base in Perevalne on March 17.
A man holds a Crimean flag as he stands in front of the Crimean parliament building in Simferopol on March 17.
Crimeans holding Russian flags celebrate in front of the parliament building in Simferopol on Sunday, March 16.
A Ukrainian police officer tries to shield himself from a road block thrown by pro-Russia supporters in Kharkiv on March 16.
Pro-Russia demonstrators storm the prosecutor general’s office during a rally in Donetsk on March 16.
A woman leaves a voting booth in Sevastopol on March 16. See the crisis in Ukraine before Crimea voted
Photos: Crisis in Ukraine
Tensions remain high as pro-Russian militants show no sign of leaving occupied government buildings in eastern Ukraine despite an international deal agreed to in Geneva, Switzerland, last week.
In his meeting with Turchynov, Biden stressed that the United States wants to stand with the people of Ukraine, according to an account of the meeting on the Ukrainian parliamentary website.
“We want to be your partner and friend, we want to assist,” Biden said. “We are not suggesting we have all the answers. We are suggesting we stand with you in every endeavor you undertake.”
Biden also issued a direct warning to the leaders in Ukraine, urging them to “fight the cancer of corruption that’s endemic” in the country.
Turchynov: Ukrainians want unity
Turchynov, meanwhile, had strong words for Moscow, saying that “Ukrainians are ready to protect their country from military aggression of the Russian Federation.”
A majority of Ukrainian citizens “are for a united, democratic Ukraine with greater powers given to the regions,” he said, referring to constitutional reforms promised in a bid to calm fears in eastern Ukraine.
Kiev and Western powers have urged Moscow to use its influence to persuade protesters in the east to lay down their arms, leave the buildings they’re occupying and accept amnesty in line with last week’s deal.
But Turchynov said Tuesday that “unfortunately, the Russian Federation and its terrorist special forces present in Ukraine are demonstratively not going to implement the Geneva agreement.”
He cited the seizure of a police station Monday in the eastern city of Kramatorsk by militants who also took the police chief hostage, “thereby negating the agreements reached in Geneva.”
Moscow has said that it holds no sway over pro-Russian protesters and militants. But Kiev and the United States dispute this.
In a phone call Monday with his Russian counterpart, U.S. Secretary of State John Kerry urged Russia to take “concrete steps” to help implement the Geneva deal and de-escalate the situation.
Russian Foreign Minister Sergey Lavrov countered by saying that Ukrainian officials were not implementing the April 17 agreement.
“On the contrary, not a single step has been taken by those who have seized power in Kiev to eliminate the reasons of this deep crisis inside Ukraine,” he said.
Ukraine: Photos show undercover Russian forces
Ukrainian officials said Monday that a dossier of photos obtained by CNN show Russian “sabotage-reconnaissance groups” acting in Ukrainian towns.
The officials said the images prove organized Russian activity in the region.
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CNN cannot independently confirm the photographs, some of which were first published in The New York Times.
The dossier shows what Ukrainian officials say are images of well-equipped gunmen in eastern Ukraine, who look similar to photographs of Russian forces taken in Crimea, Russia and during Russia’s 2008 invasion of Georgia.
Last week, Ukrainian security officials told CNN they had arrested a Russian military officer and a woman who Ukrainian officials said is a Russian intelligence agent.
Moscow has disavowed involvement in the takeover of government buildings in eastern Ukraine or other acts by often masked pro-Russian gunmen.
But the photos, accepted as genuine by the Obama administration, appeared to lend credence to allegations by Ukrainian officials that Russian forces have been dispatched in eastern Ukraine to provoke a military confrontation.
If genuine, the photos also back up Western leaders who have alleged Russia’s involvement.
The question of whether Russia is involved in the unrest roiling eastern Ukraine is crucial as European observers try to enforce the agreement reached last week in Geneva by organizing the withdrawal of forces from government buildings and other facilities.
Police station seized
Officials who brokered the deal said they hoped it would ease the crisis. But there were some signs Monday, a day after a deadly checkpoint shooting in Slaviansk, that tensions are mounting.
Residents told CNN that armed militants seized the police station in Kramatorsk, Ukraine, late Monday. The station had been stormed on April 12 before being handed back to local officials two days later.
Amateur video from the scene shows masked, armed men escorting the local police chief to a car after seizing the building.
The video, in addition to the photos released by Ukrainian officials, seemed to show that at least some forces in Ukraine show no sign of backing down.
Ukraine provided the photos to observers from the Organization for Security and Cooperation in Europe, according to the briefing dossier obtained by CNN’s Elise Labott.
Natacha Rajakovic, deputy spokeswoman for the organization, declined to comment on the images and referred questions to Ukrainian authorities.
CNN has heard Russian accents among the “men in green,” as they are known, well-armed and uniformed groups that have appeared in towns like Slaviansk and Kramatorsk. One told CNN he had come up from Crimea. But CNN has not seen any evidence that these men are operating under orders from the Kremlin.
Lavrov scoffed at the accusations Monday, saying that Kiev and its patrons, the United States and the European Union, are trying to blame his country for everything.
Meanwhile, the stalemate continues.
The government of Turchynov, the acting President, has talked tough but done little to curb pro-Russian activities in the east, possibly afraid that a crackdown could send Russian forces across the border. At the same time, the occupation of buildings continues in about a dozen towns and cities across eastern Ukraine.
In three towns, pro-Russian protesters and militants have made it clear to CNN they have no intention of moving until the “illegal” government in Kiev also moves out of official buildings.
Moscow also says the government in Kiev, installed after ousted President Viktor Yanukovych fled Ukraine for Russia in February, is illegitimate and backed by far-right extremists.
Yanukovych’s ouster followed months of street protests prompted by his decision last November to drop a planned EU trade agreement in favor of closer ties with Moscow.
Russia annexed Ukraine’s autonomous Crimea region last month, following a controversial referendum in which most voters were in favor of joining the Russian Federation.
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CNN’s Gul Tuysuz reported from Kiev and Arwa Damon from Slaviansk, while Laura Smith-Spark wrote from London. CNN’s Michael Pearson and Ed Payne contributed to this report.